Folks,
Just in case anyone is here that is not subscribed to synce-users, this
has to be read to be believed. It is a copy of the message I sent there
a moment ago:
----
Remember the problem some of you have had with WM6 when deleting a
partnership all the PIM items disappear with it? Well I have finally got
to the bottom of this now - and guess what? We are stuck with it!
That's right, it's a FEATURE, not a bug (either in our code or in
WM6)!!!!! Can you believe this! I didn't believe any software developer
could be this daft at first, until I remembered I was dealing with a
Microsoft product.
It happens with ActiveSync on Windows too.
A little more info for those who are interested:
Initially when being appraised of this problem, I spent a good few hours
analyzing wire dumps between AS and the device under Windows. Deleting
and recreating partnerships many times, I could not make PIM items
disappear. The wire dumps showed that our sync-engine code was, in fact,
operating correctly in that it was processing the partnership deletion
in the same way as ActiveSync.
However, on the Linux box it happened predictably. Initially I was
seeing sync-engine crash and naturally I assumed that the two problems
were related. A few hours later and the crash problem was largely fixed
(it seems to work more reliably if the partnership is not bound before
being deleted). However PIM items continued to be deleted with the
partnership.
And then, when examining the setup to see what was different between the
AS on Windows and the sync-engine setups, it struck me that when testing
sync-engine, I had just one partnership on the device. I was deleting
this leaving no partnerships and recreating just the one. When testing
with Windows, I created a second partnership _leaving the sync-engine
one intact_.
So I deleted all partnerships from the device, restored the PIM items,
then created just one partnership under Windows, just syncing tasks.
Then I deleted it. Guess what? All the tasks disappeared. Same happened
when I tried to sync contacts, same with calendar, same with all three.
Turns out the way it works is as follows
----------------------------------------
When WM6 creates the partnership, it creates an association between the
actual PIM data and the partnership. Now, if you create a second
partnership, syncing the same items, a second association is created
between the same PIM data and the second partnership. Now this works a
bit like a reference count.
You can safely delete/recreate/delete the second partnership and nothing
will disappear, because the first partnership holds a reference to the
PIM items. You can also delete the first partnership safely providing
the second partnership is still present. Ok so far.
Now delete one partnership, then delete the second one. Upon deletion of
the second partnership there are no more partnerships available
associated with the PIM items :- so WM6 DELETES THE PIM ITEMS!
Under Windows, it even tells you it is going to do this with the
following message, displayed in a message box with an 'Ok' button:
"Deleting the synchronization relationship with the PocketPC will remove
all the E-mail, Calendar, Contacts and Tasks information on your
PocketPC that is synchronized only with this computer the next time the
device is connected. To synchronize this PocketPC with this computer
again, you must set up a new synchronization relationship"
I guess M$ see this as a 'security feature' or something like that!
So at this point I thought I had better go on a trawl and see if anybody
in the Windows community had seen this problem. Didn't take long before
I found this thread:
http://forum.soft32.com/pda/Removing-partnership-losing-data-ftopict79766.html
Furthermore, if you have one partnership that syncs, say Contacts and
Calendar, and the second that only syncs Tasks, if you delete the second
partnership you will lose all your Tasks (there is only one partnership
that holds a reference to Tasks) and if you delete the first, you will
lose all your Contacts and Events (only this partnership holds a
reference to Contacts and Events).
Basically this is an exclusive operation, so you will only lose the item
type for which you are deleting a partnership that holds the only
reference - if another partnership holds a reference to this item type
you will not lose it.
I'm going for some coffee now, I bloody need it after discovering this
behaviour!
John.
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